Fuel cell module

ABSTRACT

A fuel cell module includes a fuel cell stack and fuel cell peripheral equipment. The fuel cell module includes a first area where an exhaust gas combustor and a start-up combustor are provided, a second area where a reformer and an evaporator are provided, and a third area where a heat exchanger is provided. The fuel cell module further includes a condensed water recovery mechanism for recovering condensed water produced through condensation of water vapor contained in a combustion gas, by flowing the condensed water through the third area, the second area, and the first area in that order.

TECHNICAL FIELD

The present invention relates to a fuel cell module including a fuelcell stack formed by stacking a plurality of fuel cells for generatingelectricity by electrochemical reactions of a fuel gas and anoxygen-containing gas.

BACKGROUND ART

Typically, a solid oxide fuel cell (SOFC) employs a solid electrolyte ofion-conductive solid oxide such as stabilized zirconia. The solidelectrolyte is interposed between an anode and a cathode to form anelectrolyte electrode assembly (hereinafter also referred to as MEA).The electrolyte electrode assembly is sandwiched between separators(bipolar plates). In use, generally, predetermined numbers of theelectrolyte electrode assemblies and the separators are stacked togetherto form a fuel cell stack.

As a system including this type of fuel cell stack, for example, a fuelcell battery disclosed in Japanese Laid-Open Patent Publication No.2001-236980 (hereinafter referred to as the conventional technique 1) isknown. As shown in FIG. 10, the fuel cell battery includes a fuel cellstack 1 a, and a heat insulating sleeve 2 a is provided at one end ofthe fuel cell stack 1 a. A reaction device 4 a is provided in the heatinsulating sleeve 2 a. The reaction device 4 a includes a heat exchanger3 a.

In the reaction device 4 a, as a treatment of liquid fuel, partialoxidation reforming which does not use water is performed. After theliquid fuel is evaporated by an exhaust gas, the liquid fuel passesthrough a feeding point 5 a which is part of the heat exchanger 3 a. Thefuel contacts an oxygen carrier gas heated by the exhaust gas thereby toinduce partial oxidation reforming, and then, the fuel is supplied tothe fuel cell stack 1 a.

Further, as shown in FIG. 11, a solid oxide fuel cell disclosed inJapanese Laid-Open Patent Publication No. 2010-504607 (PCT) (hereinafterreferred to as the conventional technique 2) has a heat exchanger 2 bincluding a cell core 1 b. The heat exchanger 2 b heats the cathode airutilizing waste heat.

Further, as shown in FIG. 12, a fuel cell system disclosed in JapaneseLaid-Open Patent Publication No. 2004-288434 (hereinafter referred to asthe conventional technique 3) includes a first area 1 c having acircular cylindrical shape extending vertically, and an annular secondarea 2 c around the first area 1 c, an annular third area 3 c around thesecond area 2 c, and an annular fourth area 4 c around the third area 3c.

A burner 5 c is provided in the first area 1 c, and a reforming pipe 6 cis provided in the second area 2 c. A water evaporator 7 c is providedin the third area 3 c, and a CO shift converter 8 c is provided in thefourth area 4 c.

SUMMARY OF INVENTION

In the conventional technique 1, at the time of reforming by partialoxidation in the reaction device 4 a, heat of the exhaust gas is usedfor heating the liquid fuel and the oxygen carrier gas. Therefore, thequantity of heat for raising the temperature of the oxygen-containinggas supplied to the fuel cell stack 1 a tends to be inefficient, and theefficiency is low.

Further, the temperature of the exhaust gas progressively decreasestoward the outer side of the reaction device 4 a. Thus, water vaporcontained in the exhaust gas is cooled, and condensed water tends to beeasily generated. Therefore, the condensed water stagnates in thereaction device 4 a, resulting in degradation of the components.

Further, in the conventional technique 2, in order to increase heatefficiency, long flow channels are adopted to have a sufficient heattransmission area. Therefore, considerably high pressure losses tend tooccur. Further, the disposal of condensed water is difficult, and thecondensed water tends to easily stagnate in the apparatus. Thus, thecomponents are deteriorated by the condensed water.

Further, in the conventional technique 3, radiation of the heat from thecentral area having the highest temperature is suppressed using heatinsulation material (partition wall). Therefore, heat cannot berecovered, and the efficiency is low. Further, the disposal of condensedwater is difficult, and the condensed water tends to easily stagnate inthe apparatus. Thus, the components are deteriorated by the condensedwater.

The present invention has been made to solve the problems of this type,and an object of the present invention is to provide a fuel cell modulehaving simple and compact structure in which it is possible to achieveimprovement in the heat efficiency and facilitation of thermallyself-sustaining operation and also it is possible to recover condensedwater reliably.

The present invention relates to a fuel cell module including a fuelcell stack formed by stacking a plurality of fuel cells for generatingelectricity by electrochemical reactions of a fuel gas and anoxygen-containing gas, a reformer for reforming a mixed gas of watervapor and a raw fuel chiefly containing hydrocarbon to produce the fuelgas supplied to the fuel cell stack, an evaporator for evaporatingwater, and supplying the water vapor to the reformer, a heat exchangerfor raising the temperature of the oxygen-containing gas by heatexchange with a combustion gas, and supplying the oxygen-containing gasto the fuel cell stack, an exhaust gas combustor for combusting the fuelgas discharged from the fuel cell stack as a fuel exhaust gas and theoxygen-containing gas discharged from the fuel cell stack as anoxygen-containing exhaust gas to produce the combustion gas, and astart-up combustor for combusting the raw fuel and the oxygen-containinggas to produce the combustion gas.

The fuel cell module includes a first area where the exhaust gascombustor and the start-up combustor are provided, an annular secondarea around the first area and where the reformer and the evaporator areprovided, an annular third area around the second area and where theheat exchanger is provided, and a condensed water recovery mechanism forrecovering condensed water produced through condensation of water vaporcontained in the combustion gas, by flowing the condensed water throughthe third area, the second area, and the first area in that order.

In the present invention, the first area including the exhaust gascombustor and the start-up combustor is centrally-located. The annularsecond area is successively provided around the first area, and theannular third area is then provided around the second area. The reformerand the evaporator are provided in the second area, and the heatexchanger is provided in the third area.

In the structure, heat waste and heat radiation are suppressed suitably.Thus, improvement in the heat efficiency is achieved, and thermallyself-sustaining operation is facilitated. Further, simple and compactstructure is achieved in the entire fuel cell module. The thermallyself-sustaining operation herein means operation where the operatingtemperature of the fuel cell is maintained using only heat energygenerated by the fuel cell itself, without supplying additional heatfrom the outside.

Further, since the condensed water recovery mechanism is provided,condensed water produced through condensation of water vapor containedin the combustion gas can flow through the third area, the second area,and the first area in that order, i.e., from the low temperature side tothe high temperature side. Thus, rechange of the condensed water intovapor state is facilitated, and accordingly the condensed water does notstagnate in the FC peripheral equipment. Therefore, condensed water isprevented from affecting the durability of the FC peripheral equipmentas much as possible, and the recovered condensed water can be utilizedas water vapor for reforming.

The above and other objects features and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings in which preferredembodiments of the present invention are shown by way of illustrativeexample.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically showing structure of a fuel cellsystem including a fuel cell module according to a first embodiment ofthe present invention;

FIG. 2 is a perspective view showing FC peripheral equipment of the fuelcell module;

FIG. 3 is a cross sectional view showing the FC peripheral equipment;

FIG. 4 is a perspective view with partial omission showing the FCperipheral equipment;

FIG. 5 is an exploded perspective view showing main components of the FCperipheral equipment;

FIG. 6 is a cross sectional plan view showing the FC peripheralequipment;

FIG. 7 is a cross sectional view showing part of the FC peripheralequipment;

FIG. 8 is an explanatory diagram of a condensed water passage hole of acondensed water recovery mechanism provided in the FC peripheralequipment;

FIG. 9 is a partial sectional side view of FC peripheral equipment of afuel cell module according to a second embodiment of the presentinvention;

FIG. 10 is a view schematically showing a fuel cell battery disclosed ina conventional technique 1;

FIG. 11 is a perspective view with partial cutout showing a solid oxidefuel cell disclosed in a conventional technique 2; and

FIG. 12 is a view schematically showing a fuel cell system disclosed ina conventional technique 3.

DESCRIPTION OF EMBODIMENTS

As shown in FIG. 1, a fuel cell system 10 includes a fuel cell module 12according to a first embodiment of the present invention, and the fuelcell system 10 is used in various applications, including stationary andmobile applications. For example, the fuel cell system 10 is mounted ona vehicle.

The fuel cell system 10 includes the fuel cell module (SOFC module) 12for generating electrical energy in power generation by electrochemicalreactions of a fuel gas (a gas produced by mixing a hydrogen gas,methane, and carbon monoxide) and an oxygen-containing gas (air), a rawfuel supply apparatus (including a fuel gas pump) 14 for supplying a rawfuel (e.g., city gas) to the fuel cell module 12, an oxygen-containinggas supply apparatus (including an air pump) 16 for supplying theoxygen-containing gas to the fuel cell module 12, a water supplyapparatus (including a water pump) 18 for supplying water to the fuelcell module 12, and a control device 20 for controlling the amount ofelectrical energy generated in the fuel cell module 12.

The fuel cell module 12 includes a solid oxide fuel cell stack 24 formedby stacking a plurality of solid oxide fuel cells 22 in a verticaldirection (or horizontal direction). The fuel cell 22 includes anelectrolyte electrode assembly (MEA) 32. The electrolyte electrodeassembly 32 includes a cathode 28, an anode 30, and an electrolyte 26interposed between the cathode 28 and the anode 30. For example, theelectrolyte 26 is made of ion-conductive solid oxide such as stabilizedzirconia.

A cathode side separator 34 and an anode side separator 36 are providedon both sides of the electrolyte electrode assembly 32. Anoxygen-containing gas flow field 38 for supplying the oxygen-containinggas to the cathode 28 is formed in the cathode side separator 34, and afuel gas flow field 40 for supplying the fuel gas to the anode 30 isformed in the anode side separator 36. As the fuel cell 22, varioustypes of conventional SOFCs can be adopted.

The operating temperature of the fuel cell 22 is high, that is, severalhundred ° C. Methane in the fuel gas is reformed at the anode 30 toobtain hydrogen and CO, and the hydrogen and CO are supplied to aportion of the electrolyte 26 adjacent to the anode 30.

An oxygen-containing gas supply passage 42 a, an oxygen-containing gasdischarge passage 42 b, a fuel gas supply passage 44 a, and a fuel gasdischarge passage 44 b extend through the fuel cell stack 24. Theoxygen-containing gas supply passage 42 a is connected to an inlet ofeach oxygen-containing gas flow field 38, the oxygen-containing gasdischarge passage 42 b is connected to an outlet of eachoxygen-containing gas flow field 38, the fuel gas supply passage 44 a isconnected to an inlet of each fuel gas flow field 40, and the fuel gasdischarge passage 44 b is connected to an outlet of each fuel gas flowfield 40.

The fuel cell module 12 includes a reformer 46 for reforming a mixed gasof a raw fuel chiefly containing hydrocarbon (e.g., city gas) and watervapor to produce a fuel gas supplied to the fuel cell stack 24, anevaporator 48 for evaporating water and supplying the water vapor to thereformer 46, a heat exchanger 50 for raising the temperature of theoxygen-containing gas by heat exchange with a combustion gas, andsupplying the oxygen-containing gas to the fuel cell stack 24, anexhaust gas combustor 52 for combusting the fuel gas discharged from thefuel cell stack 24 as a fuel exhaust gas and the oxygen-containing gasdischarged from the fuel cell stack 24 as an oxygen-containing exhaustgas to produce the combustion gas, and a start-up combustor 54 forcombusting the raw fuel and the oxygen-containing gas to produce thecombustion gas.

Basically, the fuel cell module 12 is made up of the fuel cell stack 24and FC (fuel cell) peripheral equipment (BOP) 56 (see FIGS. 1 and 2).The FC peripheral equipment 56 includes the reformer 46, the evaporator48, the heat exchanger 50, the exhaust gas combustor 52, and thestart-up combustor 54.

As shown in FIGS. 3 to 5, the FC peripheral equipment 56 includes afirst area R1 where the exhaust gas combustor 52 and the start-upcombustor 54 are provided, an annular second area R2 formed around thefirst area R1 and where the reformer 46 and the evaporator 48 areprovided, an annular third area R3 formed around the second area R2 andwhere the heat exchanger 50 is provided. A cylindrical outer member 55constituting an outer wall is provided on the outer peripheral side ofthe third area R3.

The start-up combustor 54 includes an air supply pipe 57 and a raw fuelsupply pipe 58. The start-up combustor 54 has an ejector function, andgenerates negative pressure in the raw fuel supply pipe 58 by the flowof the air supplied from the air supply pipe 57 for sucking the rawfuel. An end-side combustion portion of the start-up combustor 54 issurrounded by a tubular member 59.

The exhaust gas combustor 52 is spaced away from the start-up combustor54, and includes a combustion cup 60 formed in a shape of a cylinderhaving a bottom. A plurality of holes (e.g., circular holes orrectangular holes) 60 a are formed along the outer circumference of themarginal end of the combustion cup 60 on the bottom side. A stackattachment plate 62 is engaged with the other end of the combustion cup60 on the opening side. The fuel cell stack 24 is attached to the stackattachment plate 62.

One end of an oxygen-containing exhaust gas channel 63 a and one end ofa fuel exhaust gas channel 63 b are provided at the combustion cup 60.The combustion gas is produced inside the combustion cup 60 bycombustion reaction of the fuel gas (more specifically, fuel exhaustgas) and the oxygen-containing gas (more specifically, oxygen-containingexhaust gas).

As shown in FIG. 1, the other end of the oxygen-containing exhaust gaschannel 63 a is connected to the oxygen-containing gas discharge passage42 b of the fuel cell stack 24, and the other end of the fuel exhaustgas channel 63 b is connected to the fuel gas discharge passage 44 b ofthe fuel cell stack 24.

As shown in FIGS. 3 to 5, the reformer 46 is a preliminary reformer forreforming higher hydrocarbon (C₂₊) such as ethane (C₂H₆), propane(C₃H₈), and butane (C₄H₁₀) in the city gas (raw fuel) to produce thefuel gas chiefly containing methane (CH₄), hydrogen, and CO by steamreforming. The operating temperature of the reformer 46 is set atseveral hundred ° C.

The reformer 46 includes a plurality of reforming pipes (heattransmission pipes) 66 provided around the exhaust gas combustor 52 andthe start-up combustor 54. Each of the reforming pipes 66 is filled withreforming catalyst pellets (not shown). Each of the reforming pipes 66has one end (lower end) fixed to a first lower ring member 68 a, and theother end (upper end) fixed to a first upper ring member 68 b.

The outer circumferential portions of the first lower ring member 68 aand the first upper ring member 68 b are fixed to the innercircumferential portion of a cylindrical partition plate 70 by weldingor the like. The inner circumferential portions of the first lower ringmember 68 a and the first upper ring member 68 b are fixed to the outercircumferential portion of the combustion cup 60 of the exhaust gascombustor 52 and the outer circumferential portion of the tubular member59 of the start-up combustor 54 by welding or the like. The partitionplate 70 extends in an axial direction indicated by an arrow L, and anend of the partition plate 70 adjacent to the fuel cell stack 24 isfixed to the stack attachment plate 62. A plurality of openings 72 areformed in the outer circumference of the partition plate 70 in acircumferential direction at predetermined height positions.

The evaporator 48 has evaporation pipes (heat transmission pipes) 74provided adjacent to, and outside the reforming pipes 66 of the reformer46. As shown in FIG. 6, the reforming pipes 66 are arranged at equalintervals on a virtual circle, concentrically around the first area R1.The evaporation pipes 74 are arranged at equal intervals on a virtualcircle, concentrically around the first area R1. The number of theevaporation pipes 74 is half of the number of the reforming pipes 66.The evaporation pipes 74 are positioned on the back side of every otherposition of the reforming pipe 66 (i.e., at positions spaced away fromthe center of the first area R1).

As shown in FIGS. 3 and 4, each of the evaporation pipes 74 has one end(lower end) which is fixed to a second lower ring member 76 a by weldingor the like, and the other end (upper end) which is fixed to a secondupper ring member 76 b by welding or the like. The outer circumferentialportions of the second lower ring member 76 a and the second upper ringmember 76 b are fixed to the inner circumferential portion of thepartition plate 70 by welding or the like. The inner circumferentialportions of the second lower ring member 76 a and the second upper ringmember 76 b are fixed to the outer circumferential portion of thecombustion cup 60 of the exhaust gas combustor 52 and the outercircumferential portion of the tubular member 59 of the start-upcombustor 54 by welding or the like.

The second lower ring member 76 a is positioned below the first lowerring member 68 a (i.e., outside the first lower ring member 68 a in theaxial direction), and the second upper ring member 76 b is positionedabove the first upper ring member 68 b (i.e., outside the first upperring member 68 b in the axial direction).

An annular mixed gas supply chamber 78 a is formed between the firstlower ring member 68 a and the second lower ring member 76 a, and amixed gas of raw fuel and water vapor is supplied to the mixed gassupply chamber 78 a. Further, an annular fuel gas discharge chamber 78 bis formed between the first upper ring member 68 b and the second upperring member 76 b, and the produced fuel gas (reformed gas) is dischargedto the fuel gas discharge chamber 78 b. Both ends of each of thereforming pipes 66 are opened to the mixed gas supply chamber 78 a andthe fuel gas discharge chamber 78 b.

A ring shaped end ring member 80 is fixed to an end of the partitionplate 70 on the start-up combustor 54 side by welding or the like. Anannular water supply chamber 82 a is formed between the end ring member80 and the second lower ring member 76 a, and water is supplied to thewater supply chamber 82 a. An annular water vapor discharge chamber 82 bis formed between the second upper ring member 76 b and the stackattachment plate 62, and water vapor is discharged to the water vapordischarge chamber 82 b. Both ends of each of the evaporation pipes 74are opened to the water supply chamber 82 a and the water vapordischarge chamber 82 b.

The fuel gas discharge chamber 78 b and the water vapor dischargechamber 82 b are provided in a double deck manner, and the fuel gasdischarge chamber 78 b is provided on the inner side with respect to thewater vapor discharge chamber 82 b (i.e., below the water vapordischarge chamber 82 b). The mixed gas supply chamber 78 a and the watersupply chamber 82 a are provided in a double deck manner, and the mixedgas supply chamber 78 a is provided on the inner side with respect tothe water supply chamber 82 a (i.e., above the water supply chamber 82a).

A raw fuel supply channel 84 is opened to the mixed gas supply chamber78 a, and an evaporation return pipe 90 described later is connected toa position in the middle of the raw fuel supply channel 84 (see FIG. 1).The raw fuel supply channel 84 has an ejector function, and generatesnegative pressure by the flow of the raw fuel for sucking the watervapor.

The raw fuel supply channel 84 is fixed to the second lower ring member76 a and the end ring member 80 by welding or the like. One end of afuel gas channel 86 is connected to the fuel gas discharge chamber 78 b,and the other end of the fuel gas channel 86 is connected to the fuelgas supply passage 44 a of the fuel cell stack 24 (see FIG. 1). The fuelgas channel 86 is fixed to the second upper ring member 76 b by weldingor the like, and extends through the stack attachment plate 62 (see FIG.2).

A water channel 88 is connected to the water supply chamber 82 a. Thewater channel 88 is fixed to the end ring member 80 by welding or thelike. One end of the evaporation return pipe 90 formed by at least oneevaporation pipe 74 is provided in the water vapor discharge chamber 82b, and the other end of the evaporation return pipe 90 is connected to aposition in the middle of the raw fuel supply channel 84 (see FIG. 1).

As shown in FIG. 7, the evaporation return pipe 90 has dual pipestructure 92 in a portion thereof passing through the mixed gas supplychamber 78 a and the water supply chamber 82 a. The dual pipe structure92 includes an outer pipe 94. The outer pipe 94 surrounds theevaporation return pipe 90, and the outer pipe 94 is positionedcoaxially with the evaporation return pipe 90. The outer pipe 94 isfixed to the first lower ring member 68 a, the second lower ring member76 a, and the end ring member 80 by welding or the like, and extends inthe direction indicated by an arrow L. A gap is provided between theouter circumference of the evaporation return pipe 90 and the innercircumference of the outer pipe 94. This gap may not be provided.

The evaporation return pipe 90 may have dual pipe structure 92 a in aportion thereof passing through the fuel gas discharge chamber 78 b. Thedual pipe structure 92 a includes an outer pipe 94 a. The outer pipe 94a surrounds the evaporation return pipe 90, and the outer pipe 94 a ispositioned coaxially with the evaporation return pipe 90. The outer pipe94 a is fixed to the first upper ring member 68 b and the second upperring member 76 b by welding or the like, and extends in the directionindicated by the arrow L. A gap is formed between the outercircumference of the evaporation return pipe 90 and the innercircumference of the outer pipe 94 a as necessary. The lower end of theouter pipe 94 a is not welded to the first upper ring member 68 b.

As shown in FIGS. 3 and 4, the heat exchanger 50 includes a plurality ofheat exchange pipes (heat transmission pipes) 96 which are providedalong and around the outer circumference of the partition plate 70. Eachof the heat exchange pipes 96 has one end (lower end) fixed to a lowerring member 98 a, and the other end (upper end) fixed to an upper ringmember 98 b.

A lower end ring member 100 a is provided below the lower ring member 98a, and an upper end ring member 100 b is provided above the upper ringmember 98 b. The lower end ring member 100 a and the upper end ringmember 100 b are fixed to the outer circumference of the partition plate70 and the inner circumference of the outer member 55 by welding or thelike.

An annular oxygen-containing gas supply chamber 102 a to which theoxygen-containing gas is supplied is formed between the lower ringmember 98 a and the lower end ring member 100 a. An annularoxygen-containing gas discharge chamber 102 b is formed between theupper ring member 98 b and the upper end ring member 100 b. The heatedoxygen-containing gas is discharged to the oxygen-containing gasdischarge chamber 102 b. Both ends of each of the heat exchange pipes 96are fixed to the lower ring member 98 a and the upper ring member 98 bby welding or the like, and opened to the oxygen-containing gas supplychamber 102 a and the oxygen-containing gas discharge chamber 102 b.

The mixed gas supply chamber 78 a and the water supply chamber 82 a areplaced on the radially inward side relative to the inner circumferenceof the oxygen-containing gas supply chamber 102 a. The oxygen-containinggas discharge chamber 102 b is provided outside the fuel gas dischargechamber 78 b at a position offset downward from the fuel gas dischargechamber 78 b.

A cylindrical cover member 104 is provided on the outer circumferentialportion of the outer member 55. The center position of the cylindricalcover member 104 is shifted downward. Both of upper and lower ends (bothof axial ends) of the cover member 104 are fixed to the outer member 55by welding or the like, and a heat recovery area (chamber) 106 is formedbetween the cover member 104 and the outer circumferential portion ofthe outer member 55.

A plurality of holes 108 are formed circumferentially in a lowermarginal end portion of the outer member 55 of the oxygen-containing gassupply chamber 102 a, and the oxygen-containing gas supply chamber 102 acommunicates with the heat recovery area 106 through the holes 108. Anoxygen-containing gas supply pipe 110 communicating with the heatrecovery area 106 is connected to the cover member 104. An exhaust gaspipe 112 communicating with the third area R3 is connected to an upperportion of the outer member 55.

For example, one end of each of two oxygen-containing gas pipes 114 isprovided in the oxygen-containing gas discharge chamber 102 b. Each ofthe oxygen-containing gas pipes 114 has a stretchable member such as abellows 114 a between the upper end ring member 100 b and the stackattachment plate 62. The other end of each of the oxygen-containing gaspipes 114 extends through the stack attachment plate 62, and isconnected to the oxygen-containing gas supply passage 42 a of the fuelcell stack 24 (see FIG. 1).

As shown in FIG. 3, a first combustion gas channel 116 a as a passage ofthe combustion gas is formed in the first area R1, and a secondcombustion gas channel 116 b as a passage of the combustion gas that haspassed through the holes 60 a is formed in the second area R2. A thirdcombustion gas channel 116 c as a passage of the combustion gas that haspassed through the openings 72 is formed in the third area R3. Further,a fourth combustion gas channel 116 d is formed as a passage after theexhaust gas pipe 112. The second combustion gas channel 116 b forms thereformer 46 and the evaporator 48, and the third combustion gas channel116 c forms the heat exchanger 50.

As shown in FIGS. 3, 4, and 7, the FC peripheral equipment 56 includes acondensed water recovery mechanism 117 for recovering condensed waterproduced through condensation of water vapor contained in the combustiongas, by flowing the condensed water through the third area R3, thesecond area R2, and the first area R1 in that order.

The condensed water recovery mechanism 117 includes a first inner ringsurface 68 as of the first lower ring member 68 a forming the bottomportion of the second area R2, and a second inner ring surface 98 as ofthe lower ring member 98 a forming the bottom portion of the third areaR3. As shown in FIG. 7, the height of the bottom portion formed by thesecond inner ring surface 98 as is a dimension h higher than the heightof the bottom portion formed by the first inner ring surface 68 as.

The condensed water recovery mechanism 117 has condensed water passageholes 117 a formed in a lower portion (which is opposite to an upperportion where the fuel cell stack 24 is provided) of the partition plate70. As shown in FIG. 6, the condensed water recovery mechanism 117 hasthree or more condensed water passage holes 117 a arrangedcircumferentially. In the first embodiment, the three condensed waterpassage holes 117 a are arranged at equal angular intervals around thecenter of the FC peripheral equipment 56.

Each of the condensed water passage holes 117 a has an opening diameter(2 r) which is set to be 8 mm or more. As shown in FIG. 8, in order toflow the condensed water through the condensed water passage hole 117 a,it is necessary to satisfy an inequality P>T where P represents thetotal pressure generated in the opening area of the condensed waterpassage hole 117 a, and T represents a surface tension generatedtherein.

From the above inequality, the inequality of r×ρg×πr²>2πr×T is derivedwhere r represents the opening radius, p represents the water density, grepresents the acceleration of gravity, and T represents the surfacetension of water. Then, the inequality of r>3.85 mm is obtained, that is2r>7.7. Therefore, the opening diameter is set to be 8 mm or more.

In the partition plate 70, the upper limit of the opening diametershould preferably be set such that the pressure loss at the condensedwater passage hole 117 a is equal to or lower than, for example, 10% ofthe pressure loss at the opening 72. The upper limit can be determinedbased on the ratio of the cross sectional area of the openings 72 to thecross sectional area of the condensed water passage holes 117 a, whichis 10:1. The cross sectional areas are calculated from the number of theopenings 72 and the opening diameter thereof, and the number of thecondensed water passage holes 117 a and the opening diameter thereof.

As shown in FIGS. 3, 4, and 7, at a lower portion of the first area R1,a recovery pipe 117 b is provided adjacent to the start-up combustor 54.By connecting the recovery pipe 117 b, for example, in the middle of theraw fuel supply channel 84, it is possible to recover water vapor thatis vaporized again by the exhaust gas of the first area R1 and use therecovered water vapor for reforming.

As shown in FIG. 1, the raw fuel supply apparatus 14 includes a raw fuelchannel 118. The raw fuel channel 118 is branched into the raw fuelsupply channel 84 and the raw fuel supply pipe 58 through a raw fuelregulator valve 120. A desulfurizer 122 for removing sulfur compounds inthe city gas (raw fuel) is provided in the raw fuel supply channel 84.

The oxygen-containing gas supply apparatus 16 includes anoxygen-containing gas channel 124. The oxygen-containing gas channel 124is branched into the oxygen-containing gas supply pipe 110 and the airsupply pipe 57 through an oxygen-containing gas regulator valve 126. Thewater supply apparatus 18 is connected to the evaporator 48 through thewater channel 88.

Operation of the fuel cell system 10 will be described below.

At the time of starting operation of the fuel cell system 10, the air(oxygen-containing gas) and the raw fuel are supplied to the start-upcombustor 54. More specifically, by operation of the air pump, the airis supplied to the oxygen-containing gas channel 124. By adjusting theopening degree of the oxygen-containing gas regulator valve 126, the airis supplied to the air supply pipe 57.

In the meanwhile, in the raw fuel supply apparatus 14, by operation ofthe fuel gas pump, for example, raw fuel such as the city gas(containing CH₄, C₂H₆, C₃H₈, C₄H₁₀) is supplied to the raw fuel channel118. By regulating the opening degree of the raw fuel regulator valve120, the raw fuel is supplied into the raw fuel supply pipe 58. The rawfuel is mixed with the air, and supplied into the start-up combustor 54(see FIGS. 3 and 4).

Thus, the mixed gas of the raw fuel and the air is supplied into thestart-up combustor 54, and the mixed gas is ignited to start combustion.Therefore, the combustion gas produced in combustion flows from thefirst area R1 to the second area R2. Further, the combustion gas issupplied to the third area R3, and then, the combustion gas isdischarged to the outside of the fuel cell module 12 through the exhaustgas pipe 112.

As shown in FIGS. 3 and 4, the reformer 46 and the evaporator 48 areprovided in the second area R2, and the heat exchanger 50 is provided inthe third area R3. Thus, the combustion gas discharged from the firstarea R1 first heats the reformer 46, next heats the evaporator 48, andthen heats the heat exchanger 50.

Then, after the temperature of the fuel cell module 12 is raised to apredetermined temperature, the air (oxygen-containing gas) is suppliedto the heat exchanger 50, and the mixed gas of the raw fuel and thewater vapor is supplied to the reformer 46.

More specifically, as shown in FIG. 1, the opening degree of theoxygen-containing gas regulator valve 126 is adjusted such that the flowrate of the air supplied to the oxygen-containing gas supply pipe 110 isincreased, and the opening degree of the raw fuel regulator valve 120 isadjusted such that the flow rate of the raw fuel supplied to the rawfuel supply channel 84 is increased. Further, by operation of the watersupply apparatus 18, the water is supplied to the water channel 88. Theair is supplied from the oxygen-containing gas supply pipe 110 to theheat recovery area 106 of the outer member 55. Thus, the air flowsthrough the holes 108 into the oxygen-containing gas supply chamber 102a.

Therefore, as shown in FIGS. 3 and 4, the air flows into the heatexchanger 50, and after the air is temporarily supplied to theoxygen-containing gas supply chamber 102 a, while the air is movinginside the heat exchange pipes 96, the air is heated by heat exchangewith the combustion gas supplied into the third area R3. After theheated air is temporarily supplied to the oxygen-containing gasdischarge chamber 102 b, the air is supplied to the oxygen-containinggas supply passage 42 a of the fuel cell stack 24 through theoxygen-containing gas pipes 114 (see FIG. 1). In the fuel cell stack 24,the heated air flows along the oxygen-containing gas flow field 38, andthe air is supplied to the cathode 28.

After the air flows through the oxygen-containing gas flow field 38, theair is discharged from the oxygen-containing gas discharge passage 42 binto the oxygen-containing exhaust gas channel 63 a. Theoxygen-containing exhaust gas channel 63 a is opened to the combustioncup 60 of the exhaust gas combustor 52, and the oxygen-containingexhaust gas is supplied into the combustion cup 60.

Further, as shown in FIG. 1, the water from the water supply apparatus18 is supplied to the evaporator 48. After the raw fuel is desulfurizedin the desulfurizer 122, the raw fuel flows through the raw fuel supplychannel 84, and moves toward the reformer 46.

In the evaporator 48, after the water is temporarily supplied to thewater supply chamber 82 a, while water is moving inside the evaporationpipes 74, the water is heated by the combustion gas flowing through thesecond area R2, and vaporized. After the water vapor flows into thewater vapor discharge chamber 82 b, the water vapor is supplied to theevaporation return pipe 90 connected to the water vapor dischargechamber 82 b. Thus, the water vapor flows inside the evaporation returnpipe 90, and flows into the raw fuel supply channel 84. Then, the watervapor is mixed with the raw fuel supplied by the raw fuel supplyapparatus 14 to produce the mixed gas.

The mixed gas from the raw fuel supply channel 84 is temporarilysupplied to the mixed gas supply chamber 78 a of the reformer 46. Themixed gas moves inside the reforming pipes 66. In the meanwhile, themixed gas is heated by the combustion gas flowing through the secondarea R2, and is then steam-reformed. After removal (reforming) ofhydrocarbon of C₂₊, a reformed gas chiefly containing methane isobtained.

After this reformed gas is heated, the reformed gas is temporarilysupplied to the fuel gas discharge chamber 78 b as the fuel gas.Thereafter, the fuel gas is supplied to the fuel gas supply passage 44 aof the fuel cell stack 24 through the fuel gas channel 86 (see FIG. 1).In the fuel cell stack 24, the heated fuel gas flows along the fuel gasflow field 40, and the fuel gas is supplied to the anode 30. In themeanwhile, the air is supplied to the cathode 28. Thus, electricity isgenerated in the electrolyte electrode assembly 32.

After the fuel gas flows through the fuel gas flow field 40, the fuelgas is discharged from the fuel gas discharge passage 44 b to the fuelexhaust gas channel 63 b. The fuel exhaust gas channel 63 b is opened tothe inside of the combustion cup 60 of the exhaust gas combustor 52, andthe fuel exhaust gas is supplied into the combustion cup 60.

Under the heating operation by the start-up combustor 54, when thetemperature of the fuel gas in the exhaust gas combustor 52 exceeds theself-ignition temperature, combustion of the oxygen-containing exhaustgas and the fuel exhaust gas is started inside the combustion cup 60. Inthe meanwhile, combustion operation by the start-up combustor 54 isstopped.

The combustion cup 60 has the holes 60 a. Therefore, as shown in FIG. 3,the combustion gas supplied into the combustion cup 60 flows through theholes 60 a from the first area R1 into the second area R2. Then, afterthe combustion gas is supplied to the third area R3, the combustion gasis discharged to the outside of the fuel cell module 12.

In the FC peripheral equipment 56, the combustion gas flows through thefirst area R1, the second area R2, and the third area R3 in that order,and exchanges heat with each area. Thereafter, the combustion gas isdischarged to the outside. At that time, water vapor contained in thecombustion gas is condensed due to decrease of the temperature of thecombustion gas. The condensed water tends to stagnate, in particular,easily in the third area R3 where the temperature is relatively low.

As shown in FIG. 7, the condensed water stagnating in the third area R3moves to the second area R2 through the condensed water passage holes117 a of the condensed water recovery mechanism 117, which are formed inthe lower portion of the partition plate 70. Then, the condensed watermoves to the first area R1, and is thereafter introduced into thetubular member 59 of the start-up combustor 54. In the first area R1,hot exhaust gas has been produced, whereby the condensed water isevaporated to produce water vapor. The produced water vapor (includingthe condensed water) is recovered through the recovery pipe 117 b.

In the first embodiment, the FC peripheral equipment 56 includes thefirst area R1 where the exhaust gas combustor 52 and the start-upcombustor 54 are provided, the annular second area R2 around the firstarea R1 and where the reformer 46 and the evaporator 48 are provided,and the annular third area R3 around the second area R2 and where theheat exchanger 50 is provided.

That is, the first area R1 is provided at the center, the annular secondarea R2 is provided around the first area R1, and the annular third areaR3 is provided around the second area R2. Heat waste and heat radiationcan be suppressed suitably. Thus, improvement in the heat efficiency isachieved, thermally self-sustaining operation is facilitated, and thestructure of the entire fuel cell module 12 can be made simple andcompact. Thermally self-sustaining operation herein means operationwhere the operating temperature of the fuel cell 22 is maintained usingonly heat energy generated in the fuel cell 22 itself, without supplyingadditional heat from the outside.

Further, the FC peripheral equipment 56 includes the condensed waterrecovery mechanism 117. Thus, the condensed water produced throughcondensation of water vapor contained in the combustion gas can flowthrough the third area R3, the second area R2, and the first area R1 inthat order, i.e., from the low temperature side to the high temperatureside.

Thus, rechange of the condensed water into vapor state is facilitated,and as a result, the condensed water does not stagnate in the FCperipheral equipment 56. Therefore, the condensed water is preventedfrom affecting the durability of the FC peripheral equipment 56 as muchas possible, and the recovered condensed water can be utilized as watervapor for reforming.

Further, in the first embodiment, as shown in FIG. 3, the reformer 46includes the annular mixed gas supply chamber 78 a, the annular fuel gasdischarge chamber 78 b, the reforming pipes 66, and the secondcombustion gas channel 116 b. The mixed gas is supplied to the mixed gassupply chamber 78 a, and the produced fuel gas is discharged into thefuel gas discharge chamber 78 b. Each of the reforming pipes 66 has oneend connected to the mixed gas supply chamber 78 a, and the other endconnected to the fuel gas discharge chamber 78 b. The second combustiongas channel 116 b supplies the combustion gas to the space between thereforming pipes 66.

The evaporator 48 includes the annular water supply chamber 82 a, theannular water vapor discharge chamber 82 b, the evaporation pipes 74,and the second combustion gas channel 116 b. The water is supplied tothe water supply chamber 82 a, and the water vapor is discharged intothe water vapor discharge chamber 82 b. Each of the evaporation pipes 74has one end connected to the water supply chamber 82 a, and the otherend connected to the water vapor discharge chamber 82 b. The secondcombustion gas channel 116 b supplies the combustion gas to the spacebetween the evaporation pipes 74.

The heat exchanger 50 includes the annular oxygen-containing gas supplychamber 102 a, the annular oxygen-containing gas discharge chamber 102b, the heat exchange pipes 96, and the third combustion gas channel 116c. The oxygen-containing gas is supplied to the oxygen-containing gassupply chamber 102 a, and the heated oxygen-containing gas is dischargedinto the oxygen-containing gas discharge chamber 102 b. Each of the heatexchange pipes 96 has one end connected to the oxygen-containing gassupply chamber 102 a, and the other end connected to theoxygen-containing gas discharge chamber 102 b. The third combustion gaschannel 116 c supplies the combustion gas to the space between the heatexchange pipes 96.

As described above, the annular supply chambers (mixed gas supplychamber 78 a, water supply chamber 82 a, and oxygen-containing gassupply chamber 102 a), the annular discharge chambers (fuel gasdischarge chamber 78 b, water vapor discharge chamber 82 b, andoxygen-containing gas discharge chamber 102 b) and the pipes (reformingpipes 66, evaporation pipes 74, and heat exchange pipes 96) are providedas basic structure. Thus, simple structure is achieved easily.Accordingly, the production cost of the fuel cell module 12 is reducedeffectively. Further, by changing the volumes of the supply chambers andthe discharge chambers, and the length, the diameter, and the number ofthe pipes, a suitable operation can be achieved depending on variousoperating conditions, and the design flexibility of the fuel cell modulecan be enhanced.

Further, the fuel gas discharge chamber 78 b and the water vapordischarge chamber 82 b are provided in a double deck manner, and thefuel gas discharge chamber 78 b is provided on the inner side withrespect to the water vapor discharge chamber 82 b. The mixed gas supplychamber 78 a and the water supply chamber 82 a are provided in a doubledeck manner, and the mixed gas supply chamber 78 a is provided on theinner side with respect to the water supply chamber 82 a. In thestructure, in the second area R2, the reformer 46 and the evaporator 48can be arranged compactly and efficiently. As a result, reduction in theoverall size of the FC peripheral equipment 56 is achieved easily.

Further, the mixed gas supply chamber 78 a is formed between the firstlower ring member (inner ring) 68 a into which ends of the reformingpipes 66 are inserted and the second lower ring member (outer ring) 76 aspaced away from the first lower ring member 68 a. The fuel gasdischarge chamber 78 b is formed between the first upper ring member(inner ring) 68 b into which the other ends of the reforming pipes 66are inserted and the second upper ring member (outer ring) 76 b spacedaway from the first upper ring member 68 b.

Further, the water supply chamber 82 a is formed between the secondlower ring member (inner ring) 76 a into which ends of the evaporationpipes 74 are inserted and the end ring member (outer ring) 80 spacedaway from the second lower ring member 76 a. The water vapor dischargechamber 82 b is formed between the second upper ring member (inner ring)76 b into which the other ends of the evaporation pipes 74 are insertedand the stack attachment plate (outer ring) 62 spaced away from thesecond upper ring member 76 b.

Likewise, the oxygen-containing gas supply chamber 102 a is formedbetween the lower ring member (inner ring) 98 a into which ends of theheat exchange pipes 96 are inserted and the lower end ring member (outerring) 100 a spaced away from the lower ring member 98 a. Theoxygen-containing gas discharge chamber 102 b is formed between theupper ring member (inner ring) 98 b into which the other ends of theheat exchange pipes 96 are inserted and the upper end ring member (outerring) 100 b spaced away from the upper ring member 98 b.

In the structure, each of the mixed gas supply chamber 78 a, the fuelgas discharge chamber 78 b, the water supply chamber 82 a, the watervapor discharge chamber 82 b, the oxygen-containing gas supply chamber102 a, and the oxygen-containing gas discharge chamber 102 b is made ofthe inner ring and the outer ring, and the structure of these chambersis simplified effectively. Thus, the production cost is reducedeffectively, and the size reduction is achieved easily.

Further, the fuel gas discharge chamber 78 b, the water vapor dischargechamber 82 b, and the oxygen-containing gas discharge chamber 102 b areprovided at the side of one end adjacent to the fuel cell stack 24, andthe mixed gas supply chamber 78 a, the water supply chamber 82 a, andthe oxygen-containing gas supply chamber 102 a are provided at the sideof the other end distant from the fuel cell stack 24.

In the structure, the reactant gas immediately after heating and thereactant gas immediately after reforming (fuel gas and oxygen-containinggas) can be supplied to the fuel cell stack 24 promptly. Further, theexhaust gas from the fuel cell stack 24 can be supplied to the exhaustgas combustor 52, the reformer 46, the evaporator 48, and the heatexchanger 50 of the FC peripheral equipment 56 while decrease in thetemperature of the exhaust gas from the fuel cell stack 24 due to heatradiation is suppressed as much as possible. Thus, improvement in theheat efficiency is achieved, and thermally self-sustaining operation isfacilitated.

Further, the condensed water recovery mechanism 117 includes a firstinner ring surface 68 as of the first lower ring member 68 a forming thebottom portion of the second area R2, and a second inner ring surface 98as of the lower ring member 98 a forming the bottom portion of the thirdarea R3. As shown in FIG. 7, the height of the bottom portion formed bythe second inner ring surface 98 as is a dimension h higher than theheight of the bottom portion formed by the first inner ring surface 68as.

Thus, the condensed water can flow from the outer side (low temperatureside) to the inner side (high temperature side) of the FC peripheralequipment 56, and rechange of the condensed water into vapor state canbe facilitated. Therefore, the condensed water does not stagnate in theFC peripheral equipment 56, and it is possible to prevent the condensedwater from affecting the durability of the FC peripheral equipment 56and to utilize the recovered condensed water as water vapor forreforming.

The FC peripheral equipment 56 includes a partition plate 70 arrangedvertically between the second area R2 and the third area R3. Thecondensed water recovery mechanism 117 has the condensed water passagehole 117 a formed in the lower portion of the partition plate 70 whichis opposite to the upper portion where the fuel cell stack 24 isprovided.

In the structure, blow-through of the combustion gas can be suppressedsuitably thereby to further improve the heat efficiency, wherebythermally self-sustaining operation can be facilitated reliably.Further, the condensed water can move from the outer side (lowtemperature side) to the inner side (high temperature side) of the FCperipheral equipment 56 through the condensed water passage holes 117 aof the partition plate 70. Thus, rechange of the condensed water intovapor state is facilitated, and consequently the condensed water doesnot stagnate in the FC peripheral equipment 56. Therefore, condensedwater is prevented from affecting the durability of the FC peripheralequipment 56 as much as possible, and the recovered condensed water canbe utilized as water vapor for reforming.

Further, as shown in FIG. 6, three or more condensed water passage holes117 a are arranged circumferentially. Thus, even if the FC peripheralequipment 56 is inclined due to an installation condition or the like ofthe FC peripheral equipment 56, the condensed water can be recoveredreliably. Therefore, it is possible to prevent the condensed water fromaffecting the durability of the FC peripheral equipment 56 as much aspossible.

Still further, the opening diameter of the condensed water passage hole117 a is set to be 8 mm or more. Thus, the flow of the condensed wateris not blocked by the surface tension of the condensed water, andaccordingly it is possible to recover the condensed water reliably.Therefore, it is possible to prevent the condensed water from affectingthe durability of the FC peripheral equipment 56 as much as possible.

Further, the fuel cell module 12 is a solid oxide fuel cell module.Therefore, the fuel cell module 12 is suitable for, in particular, hightemperature type fuel cells such as SOFC.

FIG. 9 is a partial sectional side view showing structure of FCperipheral equipment 142 of a fuel cell module 140 according to a secondembodiment of the present invention. The constituent elements of thefuel cell module 140 according to the second embodiment of the presentinvention that are identical to those of the fuel cell module 12according to the first embodiment are labeled with the same referencenumeral, and description thereof will be omitted.

The FC peripheral equipment 142 includes a condensed water recoverymechanism 144. The condensed water recovery mechanism 144 includes afirst inner ring surface 146 s of a first lower ring member 146 formingthe bottom portion of the second area R2, and a second inner ringsurface 148 s of a lower ring member 148 forming the bottom portion ofthe third area R3.

The first lower ring member 146 corresponds to the first lower ringmember 68 a in the first embodiment, and the lower ring member 148corresponds to the lower ring member 98 a in the first embodiment. Thefirst lower ring member 146 and the lower ring member 148 are downwardlyinclined toward the center of the first area R1. That is, each of thefirst inner ring surface 146 s and the second inner ring surface 148 sis downwardly inclined from the outer circumferential end portion to theinner circumferential end portion. Totally, the downwardly-inclinedsurface is formed from the second inner ring surface 148 s to the firstinner ring surface 146 s.

In the second embodiment, the condensed water in the third area R3 movestoward the partition plate 70 along the inclination of the second innerring surface 148 s, and thereafter moves to the second area R2 throughthe condensed water passage holes 117 a. Further, the condensed watermoves to the first area R1 along the inclination of the first inner ringsurface 146 s, and is then introduced in the tubular member 59. In thestructure, the condensed water can be discharged more efficiently.Further, it is possible to obtain the same advantages as in the firstembodiment, for example, that heat waste and heat radiation can besuppressed suitably thereby to improve the heat efficiency, wherebythermally self-sustaining operation is facilitated.

While the invention has been particularly shown and described withreference to preferred embodiments, it will be understood thatvariations and modifications can be effected thereto by those skilled inthe art without departing from the scope of the invention as defined bythe appended claims.

1. A fuel cell module comprising: a fuel cell stack formed by stacking aplurality of fuel cells for generating electricity by electrochemicalreactions of a fuel gas and an oxygen-containing gas; a reformer forreforming a mixed gas of water vapor and a raw fuel chiefly containinghydrocarbon to produce the fuel gas supplied to the fuel cell stack; anevaporator for evaporating water, and supplying the water vapor to thereformer; a heat exchanger for raising a temperature of theoxygen-containing gas by heat exchange with a combustion gas, andsupplying the oxygen-containing gas to the fuel cell stack; an exhaustgas combustor for combusting the fuel gas discharged from the fuel cellstack as a fuel exhaust gas and the oxygen-containing gas dischargedfrom the fuel cell stack as an oxygen-containing exhaust gas to producethe combustion gas; and a start-up combustor for combusting the raw fueland the oxygen-containing gas to produce the combustion gas, wherein thefuel cell module includes: a first area where the exhaust gas combustorand the start-up combustor are provided; an annular second area aroundthe first area and where the reformer and the evaporator are provided;an annular third area around the second area and where the heatexchanger is provided; and a condensed water recovery mechanism forrecovering condensed water produced through condensation of water vaporcontained in the combustion gas, by flowing the condensed water throughthe third area the second area, and the first area in that order.
 2. Thefuel cell module according to claim 1, wherein the reformer includes anannular mixed gas supply chamber to which the mixed gas is supplied, anannular fuel gas discharge chamber to which the produced fuel gas isdischarged, a plurality of reforming pipes each having one end connectedto the mixed gas supply chamber, and another end connected to the fuelgas discharge chamber, and a combustion gas channel for supplying thecombustion gas to spaces between the reforming pipes; the evaporatorincludes an annular water supply chamber to which the water is supplied,an annular water vapor discharge chamber to which the water vapor isdischarged, a plurality of evaporation pipes each having one endconnected to the water supply chamber, and another end connected to thewater vapor discharge chamber, and a combustion gas channel forsupplying the combustion gas to spaces between the evaporation pipes;and the heat exchanger includes an annular oxygen-containing gas supplychamber to which the oxygen-containing gas is supplied, an annularoxygen-containing gas discharge chamber to which the heatedoxygen-containing gas is discharged, a plurality of heat exchange pipeseach having one end connected to the oxygen-containing gas supplychamber, and another end connected to the oxygen-containing gasdischarge chamber, and a combustion gas channel for supplying thecombustion gas to spaces between the heat exchange pipes.
 3. The fuelcell module according to claim 2, wherein the fuel gas discharge chamberand the water vapor discharge chamber are provided in a double deckmanner, and the fuel gas discharge chamber is provided on an inner sidewith respect to the water vapor discharge chamber; and the mixed gassupply chamber and the water supply chamber are provided in a doubledeck manner, and the mixed gas supply chamber is provided on an innerside with respect to the water supply chamber.
 4. The fuel cell moduleaccording to claim 2, wherein each of the mixed gas supply chamber andthe fuel gas discharge chamber is formed between an inner ring intowhich ends of the reforming pipes are inserted and an outer ring spacedaway from the inner ring; each of the water supply chamber and the watervapor discharge chamber is formed between an inner ring into which endsof the evaporation pipes are inserted and an outer ring spaced away fromthe inner ring; and each of the oxygen-containing gas supply chamber andthe oxygen-containing gas discharge chamber is formed between an innerring into which ends of the heat exchange pipes are inserted and anouter ring spaced away from the inner ring.
 5. The fuel cell moduleaccording to claim 2, wherein the fuel gas discharge chamber, the watervapor discharge chamber, and the oxygen-containing gas discharge chamberare provided at one end side adjacent to the fuel cell stack; and themixed gas supply chamber, the water supply chamber, and theoxygen-containing gas supply chamber are provided at another end sidedistant from the fuel cell stack.
 6. The fuel cell module according toclaim 4, wherein the condensed water recovery mechanism comprises afirst inner ring surface forming a bottom portion of the second area anda second inner ring surface forming a bottom portion of the third area;and a height of the bottom portion formed by the second inner ringsurface is higher than a height of the bottom portion formed by thefirst inner ring surface.
 7. The fuel cell module according to claim 4,further comprising a partition plate arranged vertically between thesecond area and the third area, wherein the condensed water recoverymechanism includes a condensed water passage hole formed in a lowerportion of the partition plate which is opposite to an upper portionthereof where the fuel cell stack is provided.
 8. The fuel cell moduleaccording to claim 7, wherein the condensed water passage hole comprisesthree condensed water passage holes which are arrangedcircumferentially.
 9. The fuel cell module according to claim 7, whereinthe condensed water passage hole has an opening diameter which is set tobe 8 mm or more.
 10. The fuel cell module according to claim 1, whereinthe fuel cell module is a solid oxide fuel cell module.